In this exclusive excerpt from his new book Fire and Rain: The Beatles, Simon & Garfunkel, James Taylor, CSNY and the Lost Story of 1970, Rolling Stone contributing editor David Browne details the much-anticipated U.K. debut of the band dubbed "the American Beatles."

On the night of January 6th, Paul McCartney settled into his seat at the Royal Albert Hall. Along with five thousand others in the elegantly domed theater with boxed seats, he was about to witness the London debut of the band everyone was calling the "American Beatles." (One of them was actually English, but a catchy press moniker couldn’t be denied.) Thirteen months earlier, George Harrison had passed on signing them to Apple, but now they were stars on a headlining tour of Europe. In one sign of their stature, their massive sound system, complete with a lighting rig specially designed for them, had arrived in London from the States by boat. They were put up in the city’s five-star Dorchester Hotel—where the grand reception party for the Beatles’ A Hard Day’s Night had taken place in now far-off 1964—and the Rolling Stones lent their managers an office in town. Whatever David Crosby, Stephen Stills, Graham Nash, and Neil Young wanted, they received.

They were a little nervous, with ample reason. All the major newspaper critics and a host of celebrities—not merely McCartney but Donovan and Ahmet Ertegun, the worldly, Turkish-born head of their label, Atlantic—had assembled to scrutinize them in person. Nash, who’d grown up in Manchester, knew some of his fellow countrymen were skeptical because he’d left the beloved Hollies and his native country to join this new band in Los Angeles. Before they began the show, they calmed their nerves by indulging in one of their pre-show rituals, a shared joint. By the time Crosby, Stills & Nash took the stage—with Young to follow later—Crosby was either so high, nervous, or energized (or some combination of the three) that he didn’t notice a stagehand slapping an "L" sign—the British learners permit for driving lessons—on the back of his brown fringe jacket as he walked out.

The audience guffawed as one; everyone knew Crosby, Stills, Nash & Young were hardly newcomers. The public had first become aware of them eight months earlier with the release of Crosby, Stills & Nash, made before Young joined up with them. The bands they’d once been members of—the Byrds, Buffalo Springfield, and the Hollies—had made some of the most dynamic, sparkling music of the ’60s. Yet the public embraced the new configuration in ways it had only occasionally taken the other bands to its bosom. The California-sun-drenched embrace of their labored-over, multitracked harmonies, the three distinctive-looking men reclining on an outdoor couch on the album cover, the variety of music from the dramatic, postapocalyptic soar of "Wooden Ships" to the turbulent churn of "Long Time Gone": Whatever it was, Crosby, Stills & Nash quickly went gold, selling a half-million copies. As 1970 began, it remained firmly lodged in the top 10 in the States.

Starting with their name, which read more like a law firm than a rock band, they wanted everyone to know they were a paradigm for a new, more liberating era in rock and roll. The group format, they insisted, had become too restrictive, too limited, too Establishment. (To hammer that point home and tweak his former life, Crosby would sometimes play a few seconds of the chimey twelve-string lick of the Byrds’ "Mr. Tambourine Man" onstage, which always drew a laugh: The Byrds? A pop group? How quaint!) As the Royal Albert Hall crowd witnessed, they didn’t even resemble a traditionally cohesive band. Crosby, at twenty-eight the veteran, had the bushy hair, serpentine walrus mustache, and stoner-bliss smile of the hippie commune leader next door. Nash, who’d be turning twenty-eight the following month, had a head engulfed in sculpted brown hair and a wardrobe of vests and floral-print shirts that embodied modish counterculture. Stills was younger than both—he’d turned twenty-five three days earlier—yet more conservative in attire (white-button shirts, dark suit jackets) and hairstyle (sideburns and prematurely thinning dark-blond hair framing chiseled cheekbones). Young, the relative baby at twenty-four, opted for patched denim and white-lace shirts. His furrowed brow and shoulder-length locks set him apart from the others as did the way he’d lurk behind them, near the guitar amps, during their shows.

After opening with "Suite: Judy Blue Eyes," the seven-minute Stills homage to former girlfriend Judy Collins that had become one of their signature songs, their utter self-confidence kicked in. As McCartney looked on, they sang one of his own songs, "Blackbird," from the White Album. They’d tackled it before, including at Woodstock the previous summer, but tonight it was a declaration of their eminence: It practically declared that they were picking up where the Beatles had left off. (To their credit, they sang it lovingly, with Stills holding a long, raspy note in the "dark black night" line that made the song their own.) The rest of the show broke with tradition in numerous ways. For the first, acoustic half, the four sang some songs as a quartet, others separately, others with a combination of the four. Like their garb, the songs mirrored their diverse personalities and lifestyles. Crosby’s "Triad" openly coaxed a girl into having a ménage à trois; Nash introduced "Our House," about the cozy, music-and-lovemaking existence he had back home in Laurel Canyon with his girlfriend Joni Mitchell. (He also told the crowd it was from a new album they’d just completed, to be called Déjà vu.) Young’s "The Loner" seemed to be as much about himself—the way he worked on his own schedule, at his own pace, on his terms—as about the song’s borderline-stalker character.

Halfway through the set, a curtain behind them parted, revealing a bowl-haired drummer, Dallas Taylor, and a very young-looking black bass player, Greg Reeves. Thus began the electric second half of the show, which shed additional light on their personalities. Stills was particularly competitive and driven, no more so than during Young’s tightly wound shuffle, "Down by the River," during which the two men jabbed at each other with their lead guitars over the course of fifteen minutes. Like the group itself, the performance was both rehearsed and ragged, teetering on the brink of chaos. Just as the tangle of guitars and rhythm section was on the verge of collapse, Nash, ensconced behind an organ and waiting patiently for his moment, shouted, "All together now!" signaling a return to the song’s chorus—and, at last, an end to the show.

Throughout the night, they remained anxious, and it showed: They exchanged in-jokes with each other and indulged in lengthy tune-ups between songs. Yet few seemed to mind. The Royal Albert Hall crowd laughed adoringly at their jokes and applauded every lapse, from the not-always-precise harmonies to the sight of the four professionals trying to decide what song to do next. (Set lists! So rigid!) They could seemingly do no wrong. Atlantic had already taken in $2 million in preorders for Déjà vu. At a company sales conference in Palm Springs, California, in January, label executives touted the album as one of its biggest potential earners of the year. CSNY would embody both the decade past and the decade to come: no rules, no restrictions, just as "free and easy" as "Wooden Ships" declared.

Back at the Dorchester, Ron Stone, a bearded native New Yorker who worked for CSNY band managers Elliot Roberts and David Geffen, noticed something odd. Reeves had sprinkled something outside the door of his room. When asked, he said it was witchcraft powder to ward off evil spirits. Hmmmm, Stone thought. What was that about? Reeves’ behavior had begun to raise eyebrows, yet no one could tell if it had to do with this heretofore-unknown aspect of his personality or the quantity of drugs everyone was now consuming.

For the time being, no one gave Reeves’ eccentricities much more thought. Introducing the bass player to the Royal Albert Hall audience a few hours before, Crosby had blissfully declared, "God smiled and sent us Greg Reeves." Amidst the intoxicating applause, plaudits from their industry, and backstage temptations, it was hard to believe God would stop beaming their way anytime soon.

Excerpted from Fire and Rain: The Beatles, Simon and Garfunkel, James Taylor, CSNY, and the Bittersweet Story of 1970. Available from Da Capo Press, a member of The Perseus Books Group. Copyright 2011.